A variety of diseases involve the hyperproliferation of cells. Cancer, for example, is a commonly known hyperproliferative disease. Cancer is a large, heterogeneous class of diseases in which a group of cells display uncontrolled growth, resulting in an invasion that intrudes upon and destroys adjacent tissues. The cells often metastasize, wherein the tumor cells spread to other locations in the body via the lymphatic system or through the bloodstream. Cancer can be caused by environmental factors or genetic factors (or a combination of both). Common environmental factors leading to cancer include tobacco use, poor diet and obesity, infection, radiation, lack of physical activity, and environmental pollutants. These environmental factors may cause or enhance abnormalities in the genetic material of cells. Cell reproduction is an extremely complex process that is normally tightly regulated by several classes of genes, including oncogenes and tumor suppressor genes. Abnormalities/mutations in these regulatory genes can lead to the development of cancer. A small percentage of cancers, approximately five to ten percent, are entirely hereditary. In 2007, cancer caused about 13% of all human deaths worldwide (7.9 million). Rates are rising as more people live to an old age and as mass lifestyle changes occur in the developing world.
Other forms of hyperproliferative diseases also exist, such as, but not limited to, polycystic kidney disease (PKD) and related cystic kidney diseases. Polycystic kidney disease (PKD or PCKD) is a cystic genetic disorder of the kidneys. There are two types of PKD: autosomal dominant polycystic kidney disease (ADPKD) and the less-common autosomal recessive polycystic kidney disease (ARPKD). Both forms cause hyperproliferation of kidney epithelial cells but neither form is a cancer. It occurs in humans and some other animals. PKD is characterized by the presence of multiple cysts (hence, “polycystic”) typically in both kidneys; however, 17% of cases initially present with observable disease in one kidney, with most cases progressing to bilateral disease in adulthood. The cysts are numerous and are fluid-filled, resulting in massive enlargement of the kidneys. The disease can also damage the liver, the pancreas, and, in some rare cases, the vasculature of the heart and the brain. PKD is the most common life-threatening genetic disease and the leading genetic cause of dialysis and transplantation, affecting an estimated 12.5 million people worldwide. In half of the people with PKD, there is no family history of the disease. However, in the dominant form of the disease, it affects multiple family members with variable times of emergence and with some variance in severity.
Other hyperproliferative diseases include fibrosis of different tissues. Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue. Fibrosis can lead to degeneration of the tissue or organ and/or loss of function if it becomes widespread and aggressive. Fibrosis plays a role in a number of diseases states in mammals, including, but not limited to, pulmonary fibrosis, idiopathic pulmonary fibrosis, cirrhosis, endomyocardial fibrosis, vascular or spinal stenosis, mediastinal fibrosis, myelofibrosis, retroperitoneal fibrosis, progressive massive fibrosis, nephrogenic systemic fibrosis, Crohn's Disease, keloid or old myocardial infarction, scleroderma/systemic sclerosis, arthrofibrosis, and adhesive capsulitis.
Such hyperproliferative diseases have been known for decades; however, effective treatments remain elusive.